[unreadable] This proposal is to request support for a Keystone Symposia meeting entitled "Molecular Evolution as a Driving Force in Infectious Diseases", organized by Edward C. Holmes and Thomas S. Whittam, which will be held in Breckenridge, Colorado from April 8 - 13, 2008. Infectious diseases have been a key driving force in evolution, both of the hosts and the pathogens. The era of genomics has made it possible to evaluate both infectious agents and their hosts at the genomic level. The evolutionary dynamics of viruses, bacteria and parasites, in their adaptive evolution to changes in host response or adaptation to new hosts is enormously complex. The burden of infectious diseases on people and domestic animals is staggering. We are only now beginning to achieve an understanding of how infectious organisms cause disease and how disease is mitigated by the complex patterns of immune response stimulated by infections. By bringing together experts in the evolution of viruses, bacteria and parasites, plus those studying host adaptation and evolution of the immune response, we anticipate that this meeting will stimulate further interaction between widely disparate lines of investigation. Infectious diseases represent a major threat to human health on a global scale. It is clear that infectious diseases have been a major driving force in evolution, for hosts and pathogens alike, and consequently current and future intervention strategies, such as the use of antibiotics and vaccines, will change the selection pressures acting on pathogen populations, perhaps changing virulence in turn. This symposium will stimulate further interaction between divergent lines of investigation, providing a new synthesis for the study of microbial infections and their host organisms. [unreadable] [unreadable] [unreadable]